Power transmission



April 30, 1940. H. THoMA POWER TRANSMISSION Filed Oct'. 1l, 1934 5 Sheets-Sheet 1 INVENTOR BY 1 ATTORNEY April 30, 1,940. V H. T'HQMA 2,198,891

l POWER TRANSMISSION Filed Oct. ll, 1934 5 Sheets-Sheet 2 A44/v5 ZIM/7,4

ATTORNEY April 30, 1940.

H. THoMA FQwER TRANSMISSION Filed Oct. l1, 1954 5 sheets-sheet s BRA KING P05/770A( INVENTOR /r/vs 79mm BYJM( ATTORNEY April 30, 1940. H, 'rx-IOMA 2,198,891

PowER TRANSMISSION Filed 06f. ll, 1934 5 Sl'leel'fS-Sl'lte1.r 4

arm-wwf INVENTOR H//V' THU/Wl ATTORNEY April 30, 1940. H.' THoMA 2,198,891

POWER TRANSMISSION Filed OCTu 11, 1934 5 Sheets-Sheet 5 /23 NIH] f7) INVEN-roR #AA/.s f90/1,4

'Patented Apr. 30, 1940 UNITI-:o- STATEs PATENT OFFICE 10 Claims.

This invention relates to improvements vvin power transmissions, and has for an object to provide a transmission device adapted to perform the functions Iof the usual clutch and transmission mechanism of automobiles, although the invention is capable of application to aeroplanes, boats, ships, locomotives, machine tools and any other devices where it is desired to control the utilization of power delivered by a prime mover. Among the requirements tovbe satisfied by such devices is that the energy delivered by a power supply shaft is transmitted Vto a powerdelivery shaft at variable speeds and with a torquevary- Aing inversely as the ratio of the speed of the power delivery shaft to the speed of the power supply shaft.

'It is another object of this invention to secure these results by hydraulic means consisting of a hydraulic displacement device which at certain times delivers a fluid such as oil to another y hydraulic displacement device, and vice versa.

. means for controlling said valve mechanism.

Another object is the provision of such a transmission'mechanism so constructed and arranged that the major portion of the mechanism rotates at the same speed as the power supply shaft so that said mechanism will serve the purpose of the usual fly-wheel necessary in connection with certain prime movers such as internal combustion engines.

Another object is to provide such a hydraulic transmission which may be manually controlled to provide a plurality of speed-torque ratios under manual control but which can be readily adapted for automatic operation under the control of speed responsive devices.

Another object is to provide such a transmission furnishing at least three speed-torque ratios with only two hydraulic displacement-devices.

Another object is to provide such a transmission having an overdrive, for driving the driven shaft at a greater speed than the driving shaft.

Another object is to provide such a device, adapted at certain times to be used as a hydraulic brake.

Another object is' to provide means for control- (Cl. Bti-,53) v ling the operation of such a transmission operated'by the speed of the engine and/or the car and preferably modified by the extent of opening of the throttle of the engine and/or provided with manual modifying means.

Another object is to provide such a transmission mechanism adapted'for cooperation with a mechanical transmission means of known or suitable construction.

Other objects are to improve the construction, to reduce the cost thereof and to provide such a mechanism which is reliable and durable, and

operates with high over-all efilciency.

'I'he characteristics of the present' invention are exempliiied by the device shown in the ac'- companying drawings, wherein:

Fig. 1 represents an illustrative embodiment of the invention in generally vertical longitudinal section, the section through the hydraulic devices being taken on the line I-I of Fig. 2;

Fig. 2 is a cross section taken on the line 2-2 of Fig. 1 looking in.the direction of the arrows;

Fig. 3 illustrates any'suitable supplementary mechanical transmission device being taken Von line 3-3 of Fig. 1;

Fig. 4 is a schematic view showing the control valve in .the braking position, i. e., where the.

propeller shaft speed is being retarded;

Fig. 5 shows a view similar to Fig.`4 with th valve in the neutral position, i. e., where no power is transmitted;

Fig. 6 is such a view showing the valve in the 'position where power is transmitted at a reduced speed ratio and an increased torque ratio; Fig. 7 shows ther valve in position for direct drive of the power delivery shaft by the power supply shaft;

Fig. 8 shows the valve in over-drive position;

Fig. 9 is a partly schematic view similar to Fig. 4 with the control valve in the over-drive position (Fig. 8) and also showing oil supply pumps and connections for changing the working fluid and for controlling the positioning of the control valves;

Fig. 9a shows a modification of part of the mechanism of Fig. 9;

Fig. 10 is a partly schematic view similar to Fig. 9 but showing a modified valve controlling means; and

Fig. 11 is a detail cross-sectional view taken on the line ll--ll of Fig. 10.

In said drawings, the numeralll represents a power supply shaft which maybe any'means for delivering power to the transmission and which, when the transmission is used for automay carry the usual ring gear 23 to cooperate with the usual starting motor of the automobile. Firmly attached to said `disc 22h as by a series of bolts 24 are the discs 25, 26, 21 and 28.

In the form illustrated, the hydraulic displacement device generally indicated by the n u.

mei-al P1, consistsof the central sun gear 3|) meshing with one or more planetary gears 3|, in the present instance shown as two in number, see Figs. 1, 2 and 4. The sun gear 30 is journaled coaxially with the shaft 2| and is connected.

for rotation with the power delivery shaft 32. The plate 25 is cutaway at its center to provide clearance fo. the gear V3|) and also has two preferably oppositely spaced circular clearance spaces for receiving the gears 3|. Said plate 25 is also provided with clearance spaces P11 and P1D which serve as fluid passages. It will be readily understood that any relative rotation of the gear 30 to the plate 25 will cause a rotation of the gear 30 relativel to thegears 3| whereby the gears 30 and 3| will operate as a pump. The rearward side of said fluid pump orother hydraulic displacement device P1 is closed by the plate 26.

The hydraulic displacement device generally designated P2, as shown more specifically in Figs. l, 2 and 4, acts under certain conditions as a motor and comprises a central sun gear 40 mounted coaxially with the shaft 32 and between the plates 26 and' 28. Said plates 26 and 28 are separated by the plate 21 which has central and eccentric cut-out portions similar to those in plate 25. Surrounding said gear 40 are one or more gears 4| (here shown as two in number), each meshing with 4the gear 40. 'The planetary gears 3| and 4| are journaled for rotation upon suitable shafts, which in the form shown are the bolts 24 which as stated above also hold the discs 22b, 25, 26, 21 and 28 together.

The sun gear 40 is shown as connected, as by a square jaw clutch, to a sleeve 42, which may be rigidly connected to the housing 45 through suitable means such as a set screw 44 engaging a ange 43 on said sleeve 42. In the particular form of the invention shown in the drawings the sun gear 40 will, therefore, always be stationary.

One or more Working fluid control valves V are provided. As shown these are piston valves which are longitudinally movable in valve port sleeves 50 rigidly mounted in a suitable opening in the discs 25, 26, 21 and 28. The valves arel shown provided with suitable enlargements or collars V1, V2, V3 and V1 which cooperate with suitable ports as a, b, c, d, e and f in said port sleeve 50. Said ports are connected through passages, located for the most part in the discs 22h, 25, 26, 21 and 28 to the intake and delivery sides of the devices P1 and P2, in a manner which is apparent from Fig. 4 where said passages are shown schematically. As shown in Fig. 4 the normal fluid delivery side P1D of P1 is connected to the port c by passage C and the normal fluid intake P1I of P1 is connected through passage AF to passages A and F which connect with ports a and f, respectively. Also the normal fluidV de livery side PzD of P2 is connected to port d by passage D and its intake side P21 to port b by passage B. 'Ihe opening e is not connected directly to the devices P1 or P2 and it comes into operation only while using the hydraulic brake.

From the preceding description, it will be noted that the .parts 2|, 22, 22a, 22h, 24, 25, 26, 21 and 28 all rotate together, their masses serving as a flywheel and carrying along with them gears 3| and 4| as well as the valves V. In the absence of working uid, or when working fluid is present r and it is free to circulate as desired, it is obvious larly, the circulation between PzD (Fig. 4) and P21 (Fig. 4) is unobstructed. The gear 4|), being held stationary, will merely cause oil to be pumped idly.

If now the valve V is moved to such a position (see Fig. 6) that the delivery passages P1D of the device P1 are connected to the intake passages PQI of the device Pz and the delivery passages P11D of the device P2 are connected to the intake passages P1I of device P1, the device P1 will act as a pump and will pump the working fluid through device P2 which now acts -as a. motor. The capacity of Pz being less than that of P some of the oil which is pumped by P1 per revolution cannot be accommodated by P2, as a result of which part of the motion of the driving shaft 2| must be passed on to the driven shaft 32 which therefore operates at a fraction of the speed of the engine. The oil pressure acting in P2 between the abutment provided by the stationary gear 40 and the gears 4| serves to add torque to the driving shaft which is in turn passed on to the driven For direct drive (see Fig. '1) it is merely necessary to lblock flow of oil from the delivery side P1D of P1 to the intake side P11, whereupon the sun gear 30 and the shaft 32 will be carried along at engine speed. At this time the delivery and intake sides of P2 may be connected so `that the oil is merely pumped idly.

For over-drive P2 is caused to pump working fluid into that side of P1 which normally is the deliveryvside with the result that gear 30 and shaft 32 are caused to rotate at a speed higher than engine speed, with, of course, a corresponding decrease in torque. y

The operation of valve V will now be described with special reference to Figs. 4 to 8 inclusive.

We will first assume that the -valve or Valves V are in the position shown in Fig. 5. It will be readily seen that both P1 and vP2 are short circuited. P1 may pump oil from its deliveryside P1D in through port c and out of port a back to the intake side P11. Similarly P2 may pump oil from its delivery side P2D in through port d, out ofl port f, back into port a, out through port b and back to its intake side P21. When the piston V is movedv toward the rear to the position `shown in Fig. 6 the low ratio drive is provided for. In this condition P1 pumps oil in through ports c out through port b to the intake side of P2 which acts as a motor and increases the torque of the driving shaft, thus providing a reduced ratiol with torque increase. Uponleaving the -delivery side PzD the oil passes through D, in throughv shown in Fig. I the delivery side of P1 is blocked thus causing the, driven shaft 82 to lbe carried along at the speed of shaft 2l. The oil pumped by P1 passes in at d out at fin at a out at b and back to Pz., y

With the valve V in the position of Figs. 8 and 9 Pz acts as a pump and pumps oil into the delivery side of P1 (in through port d and out through port c), then through P1 and out at P1I (in through port a and out through port b) and back to the intake side of Pa. Thus an over-drive at lower torque is achieved.

The means for controlling the position of valve V will now be described.

The various required positions of valve V may be secured manually or by any suitable control means. One 'such means is shown in Fig. 9 and a modified form is shown in Fig. 10.

Referring to Fig. 9 the device 60 is any suitable uid pressure actuated device such as a piston 6| operating in cylinder 6|. In order to furnish adjustment the spring 62 may be provided. 63 as any suitable spring support and 64 an adjustment device such as a set screw.

In the form shown the control of the valves V is effected by (a) speed of driving shaft, (b) speed of driven shaft, (c) extent of throttle opening (d) a settable over-riding control determining the limits within which automatic speed ratio changes may be made, (e) a manual setting device to vary the speed at which the change of valve position will occur, and (f) a manually operable over-riding control device such as the foot pedal FP for forcing at will a lower speed ratio than that called for by the automatic control device, including neutral and also hydraulic braking.

EP is any suitable pump such as the usual lubricating oil supply pump of an automobile engine serving to drawA oil through intake passage 10 from a suitable reservoir 1| which may lbe the usual crank case oil sump of an auto- When the motor runs, oil is de-` mobile engine. livered through passages 12, 13 to the bearings of the motor, etc. in the usual way and through check valve 14 into the rear engine bearing and around the engine shaft into the transmission through passages 15 and 15a and through check valves 16 into various parts of the transmission. As shown there are four such check valves, 161, connected to P1I, 162 connected to P1D, 16a connected to P21 and 164 connected to P2D. Not all of these are necessary but by providing these four, entry of fresh cool oil into the transmission is assured under all conditions of operation as not all of the passages P11, P1D, P21 or P2D are under high pressure at any one time. Oil discharge may occur from P11, as shown, through passage 11 which may be formed in part in one of the connecting bolts 24, as appears from Fig. 1. Another part of said passage 11 lies in the rearward tubular extension 281 vof the disc 28. As shown in Fig. 1 the member 281 carries'for rotation therewith the valve operating spider 80 mounted upon which is the non-rotary collecting ring 18 (Figs. l and 9). The oil which enters said ring from said passage 11 passes from said collecting ring 18 through passage 19 back to the crankcase, although it is preferably first led into the mechanical transmission for lubrication purposes and then permitted to drain back into the crankcase. Upon reversal of torque, as when the car drives the motor, P11 becomes subjected to high pressure. In order to avoid the escape of too much oil under these conditions the valve 18a may be provided. It is normally heldin the position shown, by spring 18h but if the pressure exerted through passage 18c exceeds a certain value it moves the valve 18a to the right and cuts off the egress of the oil (through 19) or reduces it to a proper value.

After the transmission is properly lled oil is forced through passages 85, 86, 81, 88 and 85 into cylinder 6|. When the pressure rises sumciently the piston 6|' is pressed outwardly, thus moving the valves V gradually to the low speed position and thus gradually starting'the car in motion.

In the form` shown a second oil control pump CP driven in association with the Cardan shaft 200 is provided. 'I'his pump does not begin to operate until the car moves. The oil pressure furnished thereby may work in cooperation with that o f pump EP or in substitution therefor as shown. Pump CP is shown as drawing oil from the reservoir through passage 90 and pumping it through passage 9|, adjustable throttle valve 92, passages 93, 95, 96, 91, 88 and 65 to cylinder 6|, where it exerts a certain pressure. Some of the oil passes from 96 through 98, metering valve |00, passages and 85 into the rear crankshaft bearing and then into the transmission proper. When the speed of pump CP has reached a certain value the pressure drop at the throttle valve 92 reaches a value at which the control valve piston |05, slidably mounted in a cylinder, as

shown, is moved to the left (Fig. 9) against the action ofr spring |08 through application of pressure throughpassages |02 and |03. This motion causes the reduced section |01 to be moved to the left cutting off communication between 85 and 86, and opening a passage from |02 through |04 to 81. The speed of pump CP influenced to a certain degree by the speed of pump EP will now determine the pressure on piston 6|' andthe setting of valves V.

As shown in Fig. 9 a connecting tube or passage 94 may be provided between passage 95 and the cylinder space to the left of piston valve |05, |06, I 01 whereby the said piston valve will be influenced by the pressure drop at the throttling y valve 92 as Well as by the spring |08.

Further automatic control under the influence of the accelerator pedal A. P. or other suitable throttle control may be effected by varying the opening of metering valve |00. This valve may comprise the piston valve 99 cooperating with a generally V-shaped valve port so that the area of the opening will b e varied as required, by the position of the piston 99. The latter may be positioned by a link connected to a lever 2 one end of which is connected by link ||3 with the throttle opening (accelerator) pedal A. P. To secure adjustment the other end of lever ||2 may be connected as by link ||4 to lever ||5 adjustable over an indicating scale 6, the lever and scale ||6 being preferably located on the instrument board. The lever ||5 will, of course, be held in the position to which it is set by the operator by any suitable means such as friction at Aits pivot, or by any other suitable holding means. 1

In this way the car speed at which speed ratio changes are caused to occur is made dependent upon the throttle opening. For example, if the car is running on level ground and a certain speed is reached with a small throttle opening the valve. |00 is almost closed so that the pressure in cylinder 6| is comparatively high and shifting to a higher speed ratio occurs at a lower speed. If the pedal A. P. is depressed a substan- 50 pedal FP.

70 above.

tial amount as on a hill the opening of ,valve |05 is greater and/shifting does not occur until a higher speed is reached. Furthermore, if the lever ||5 is set to the extreme counterclockwise 5 position the valve |00 is so far open that not suficient pressure is developed in the cylinder 5| to shift the v'alve out of neutral position.

To furnish a further manual control the piston 5| is preferably caused to operate against l a spring |20 the setting of' which may be readily adjusted manually. Such a construction is shown in Fig. 9. 'I'he spring |20 is preferably located within an oil filled housing |2| connected at one end to an arm 60h associated with the foot l5 pedal FP and receiving a rod |22 having a shoul- 'Ijle casing is preferably filled with oil to pro- )vide a damping action. .The rod |22 may be con- 'nected to a member |28 of a setting device |29 which may be heldin, say, five positions of adjustment, brake, neutral, low, direct and 25 Y over-drive. If in the latter position, the valves V remain in over-drive` position (assuming that the foot pedal FP is not depressed). If in direct position it is automatic in operation as between direct and over-drive. When in low position, the automatic operation is limited to direct and over-drive. When in neutral position, the'transmission will be fully automatic. When in brake position the hydraulic brake may be made effective. These results are, of

course, produced .by the balance between the spring |20 and the pressure on'plunger 50. It will be noted that this arrangement will permit of elongation or shortening of the connection between` |28 and 50h, each being resisted by spring Positive, over-riding control can be secured by `l depressing thel pedal FP to the desired extent to secure in succession direct, lowneutral and, if

depressed all the way, so as to force the valves 45 V to the positionof Fig. 4, a hydraulic braking l Hydraulic braking When the valves V are in the positionV shown in Fig. 4 hydraulic breaking occurs. At this 55 time the engine throttle will, of course, be closed and the engine will attempt to idle. The ilow of oil is shown in Fig. 4 by arrows. It will be noted that the ow from d to ,f is almost cut off so that a high pressure (say 150 atmospheres) is presso ent at PzD and the passages connected therewith, whereas the pressure at P21 is much less (say 50 atmospheres).` This pressure difference is due to the fact that the pump gears 4| are revolved around the stationary pump gear 40,

55 pumping oil which is throttled at the point f.

This pressure difference obviously results in a great deceleration torque which is transferred `to the chassis. through the sun gear 40 which is rigidly connected to the housing'45 as described However, this decelerating torque is applied to the engine whereas it fshould'be applied to the car itself as otherwise the only eect of this hydraulic braking would be to stop the engine or to rotate it reversely. It is necessary to f5 decelerate the' car itself, i. e., shaft 32. As the equal.

flywheel is decelerated the motor runs slower than the shaft 32 and as the relative rotation is reversed the normal suction PiI of the large pump becomes the pressure side (a pressure of say 50 atmospheres) whereas PiD is under considerably lower pressure. 'I'his pressure difference applies a forward torque to the motor whereas the throttling of Pz applies a reverse torque. So that the motor speed may not be too low nor too high the pressure differences should be maintained at a certain value. Assuming that P1 has about twice the displacement of Pz the following pressure condition might be regarded as typical. P3D say l150 atmos., PzI say 50 atmos. .(diiference 100 atmos.), P11 say 50 atmos., P1D

say 1 atmos. (difference approx. 50 atmos.). As

P1, is say double the displacement of Pz the two opposing torques acting on the motor are about PzI and PiI are in communication at ports a and b and since the now from both is toward the valve the pressure is substantially equal whereas the pressure at PiD may be as low as'that stated, due to the throttling action at port c. In order to maintain a proper pressure difference the valve |40I is provided. This may have one or more clearance cuts |4| and be provided with an enlarged head or piston |42 in cylinder |43 which is connected with port f and therefore with P11 through passages |44 and |45, whereas the lower end of said piston valve |40 is through passage |45 subjected to the pressure of PnD. The ratio of the area of the piston |40 to piston |42 is selected as inversely to the pressure ratios desired. Thus if the pressure desired in space |45 is three times that in space |45 (i. e., port f passage F and P11) the area of piston |40 is made one third of the area of piston |42. If the pressure in |45 shoulddrop below one third of the pressure in |45 the valve moves to the right, opening a passage at |4| (in parallel with the throttling passage at i) thus allowing oil to flow through |4| into passage |45 and raising the pressure to the desired point. When the desired pressure ratio has been reached the pressure in |45 acting on piston |42 overcomes the pressure in |46 acting on the piston |40 and shuts off the passage |4|. The piston valve |40 will therefore always be so positioned as to automatically provide for the desired pressure ratios, so that the forward and reverse torque acting on the motor flywheel will be balanced. The passage e is merely provided to connect the space |45 with the port d (connected to PzD).

In order to provide for progressive braking the piston |50 is provided. 'I'his is subjected to the pressure in PzD and its motion may be limited as by the enlarged head |5I. 'Ihis piston or plunger |50 is so located or connected that when the valves V move from the neutral" to the braking position the plunger is moved against the pressure of PzD. In this way vigorous braking occurs only when the operator applies a strong pressure to pedal FP, since the hydraulic braking pressure reacts against pedalFP. In this way too .vigorous braking is avoided and the retarding torque is generally proportional to the pressure applied by the operator to pedal FP. The head ,|5| is not at all necessary as it may be desirable to have the plunger |50 act not only during hydraulic lbraking but also in one or more of the other positions of valves V. v

In addition, or in the alternative, a relief valve may be appropriately placed as between P1I and PiD. As shown in Fig. 9 this may be a check valve |50 held in place on its seat by a normally lightly tensioned. spring |6| which is backed up by the plunger |62, the -rear side of which is subjected ,to the pressure 'of PiI. In view of this ,arrangement,a smooth kretarding effect can be produced by moving the pedal FP to the low ratio position in whichevent there will be momentary free wheeling but as the pressure in P11 gradually increases and the tension on spring |6| increases thev short circuit ow is gradually decreased so that the motor acts as a brake for the car. This is especially valuable in descending long hills. If a more vigorous braking is desired this can be accomplished by pressing the pedal FP to the hydraulic braking. position.

A modified form of relief valve is shown in Fig.

y9a which differs only in that the spring I6 la normally bears on the valve member |60a with considerable pressure and there' is no pressure controlled means for increasing the spring tension.

Both forms of valve have as an object that depression of pedal FP when the car is traveling at high speed cannot suddenly apply a largereverse torque which might result in skidding or other serious accident. If the port of these valves of Fig. 9a is made sufllcientlylarge free wheeling action is available.

With certain motors the lubricating oil pressure rises very rapidly, particularly when very cold, so that shifting from neutral to low gear may occur too early. To avoid this it may be desirable to provide a speed controlled bleeder valve. This valve may be controlled by speed in any desired way but it is preferred to utilize the generator current for this purpose. To this end a valve |10 may be provided of any suitable construction which will normally keep open a passage from the passage 88 to the crankcase or other oil reservoir. Said valve may be closed by magnetic means such as by an armature |1| cooperating with a coil |12 in series or parallel with the circuit of the generator |13. This assures that the shift from neutral to low cannot occur until a certain engine speed has been reached.

It may be desirable to assure that when the piston 6|' and/or the parts actuated thereby has moved part of the way from one position to the other at least as between neutra low, direct and over-drive. the motion be completed, so that the valves V cannot remain, for'any length of time, in an intermediate position. This may be accomplished by providing a detent device such as a serrated member carried by the lower end of lever 60a cooperating with a spring pressed detent plunger |.16 shiftably supported in a. stationary'cylinder |11.

The hydraulic transmission described above may, of course, be used in connection with a mechanical transmission to achieve either direct drive from the power delivery shaft 32 to the Cardan shaft 200 or to achieve a reduced drive or a reverse. Any suitable mechanical transmission may be utilized. In the drawings, this may consist of a gear member 260 attached to the rearward end of shaft 32, which gear 260 is continually in mesh with the gear 264 suitably mounted in the transmission housing. To said gear 264 is rigidly connected a gear 265 as shown. Splined to the Cardan shaft 200 is a gear member 266 having spur gear teeth 263 and internal teeth 262 which may cooperate with external teeth 26| on the member 260. It will be noted that if the gear member 266 is in the forward position the teeth 26| and 262 will interengage, causing the shaft 32 to drive the shaft 200 in a forward direction and at the same speed. However, if gear 266 is moved toits extreme rear position teeth 262 lwill be disengaged from teeth 26|. and gear teeth 263 will engage with gear 265 so that shaft 200 will be rotated forwardly at reduced speed; throughgearelements 260, 264, 265 and 263. If the member 266 is left in an intermediate position land the gear 212, splined to shaft 200, is shifted to engage the gear 213a the shaft 200 willbe operated in reverse direction. 'I'his is effected through gear 213 xedly connected with gear 213a and which is constantly iny mesh with gear 265. 'Ihese elements and the shifter plates 266a and 212a as well as the shifter y21| are well known and form no part of the present invention and need therefore not be described further. As shown the member 200 preferably carries a gear.280 meshing with gear 28| mounted to turn shaft 282 for driving the oil pump CP shown in Fig. 9. f

The modified form of valve control mechanism shown in Fig. y10 will now be described. This construction diiIers from the one shown in Fig. 9 in that there is no oil pump driven by the Cardan shaft. Instead there is a single pump 300, driven preferably by the power supply shaft, i. e. the engine shaft. In the form shown this pump comprises a central gear 30| meshing continuously with the gears 302 and 303 and forming with said gears 302 and 303 respectively a double gear pump. As shown the pump 30|-303 has con-l nected thereto an intake pipe 304 and a delivery 'pipe 306 connecting with tu-be 308, an extension 3|0 of which connects with a uid pressure actuated device for shifting the position of the valves V. 'I'his device may comprise piston 6|', cylinder 6|, spring 62, spring support 63, and an adjustment device such as set screw 64, these parts being shown as identical with corresponding parts in Fig. 9. Tube 306 preferably connects also with tube 3|2 connected `to pressure relief valve 3 I4 having a passage or tube 3 I6 connecting to the oil reservoir 3|8. Thepurpose of the pressure relief valve 3|4 is to assure that the pressure in the pump system does not exceed a certain value. l r

The pump 30|-302 has an intake tube 320 and a delivery tube 322 connecting with oil supply passage 13 for supplying oil to the motor bearings, etc., and with passage 312 corresponding with passage 12 in Fig. 9, which passage 312 connects via check valve 14 with the passages 15 and 15a already described'in connection with Fig. 9. 'I'he numeral 330 designates generally a metering valve which may consist of a cylinder 332 containing a piston 334 urged to the right by spring 336. Said piston 334 is' adapted to cooperate with a generally triangular cutaway portion 338. Tube 308 connects with tube 340 to permit entry of oil to the metering valve whereas tube 85 serves as an oil delivery passage from the valve to the passage 15. It will be seen, therefore, that pump 30|-302 serves primarily to supply oil to the engine bearings and to keep the hydraulic transmission properly filled. Pump 30|-,303 pumps oil or other working fluid through passages 306, 308, 340, metering valve 330', and passage 85 into the transmission.

In any given position of metering valve 330 the pressure in the system will be in some proportion to the speed of the power supply shaft and through passage 3|0 pressure is applied to the piston 6|'. Said piston 6| may be connected to operate an arm 350 which is connected for operating the spiders 80 and therethrough the valves this purpose is shown more or less schematically` ping device 312 associated with rod 356.

be by direct connection, although it is preferred to provide a manual setting device such Aas the arm I I a settable over a scale I l6a, the upper end thereof -serving as an abutment for the lever 4of the secon'd class ll2a, to the other end of which is attached the link II3 and which carries intermediate its ends some means for adjusting the `position of piston 334. Insofar as the mechanism a reduction in the oil pressure in cylinder 6| which might permit the return of valves V to the lower speed ratio position. In order to prevent this, means have been provided to assure that when a shift of the valve operating mechanism occurs, whether this is to be toward higher lspeed ratios or toward lower speed ratios, the

metering valve 330v will be adjusted to `favor the shift which is taking place. A mechanism for and may comprise a rod 356 carrying the wedgeA member 354. Suitable friction gripping means for said rod are provided which may comprise a cylinder 358, supported upon any stationary part of the vehicle, and a piston 360 operated by arm 362 having a detent 364 cooperatingy with a series of notches 366 in any suitable member 361 connected for operation with the member 350. The cylinder 358 may be provided with any suitable abutment as the edge 359- of an opening therein between which and the piston 360, the rod 356 is gripped. The member 361 may have an extension 368 which through suitable means, such as link 310, connects with a friction grip- This device may consist of a cylinder 313 provided with a spring pressed detent 314, as shown.

The operation of this control mechanism will now be described. In the position shown the valves V are in neutral. Assuming that the enginel speed is increased to a point at which, in

the assumed positionl of valve 330, the oil pres-l sure in 308-310 reaches a point at which the piston 6 I is operated and the valves V slowly shifted to higher gear position, the member 361 will be moved clockwise. During this motion the arm 362--364 will be-'momentarily rocked counterclockwise as the detent shifts from the notch shown into the next higher one. During this period the rod 356 is released for motion. At the same time the arm 368 is being shifted downj ward causing members 31|) and 312 to be shifted downwardly thereby shifting the rod 356 down'- wardly. 'This results in a downward motion of wedge 354 which causes the metering valve to be slightly closed, thereby increasing the oil pressure in 308-3I0, or at least preventing the drop in speed, of the motor from causing a decrease in the oil pressure. The same efl'ect occurs during shifting to Astill higher speed ratios.-

Assuming that the valves V positioned for one of the higher speed ratios and the engine speed drops below a certain point, a decrease in oil pressure will cause the valves V to be shifted to a lower speed ratio position. During this time the gripping element 360 is temporarily released permitting the upward shifting of member 312 to raise the rodA 356 and wedge 354 and thereby cause the metering valve 330 to be opened further so as to compensate for the increase in engine Speed which will now occur.

s It will be seen, therefore, that the'metering valve 330 may be controlled by (a) throttle opening; (b) the manual setting device H5a; and (c) b'y changes in the position of the valves V. Furthermore, the mechanism always works in favor of maintaining the position to which the latest shift has occurred whereby unnnecessary shifting of valves V or hunting" is avoided.

YThe valve operating mechanism may also be manually controlled as by foot pedal 360 having a one-way connection with members 350, 352-361, as through the adjusting screw 382. The foot pedal 383 is preferably connected with member 361 as by spring 384 and is provided with a retaining dog 385 cooperating with one of a plurality of shoulders 388 located on stationary member 381. Whenthe foot pedal 380 is in rearmost position the operation of the transmission is fully automatic but ifl the pedal is depressed the valves V may be forced to a lower speed ratio position such as direct, low or neutral and a further depression of the foot pedal will cause a compression of spring FS and the shifting of the valves to hydraulic braking position.

With reference to Fig. 9 it will, of course, be understood that the pumps EP and CP, as well as all the parts shown in full lines as connected therewith, are carried by the chassis whereas those elements shown in dotted lines are carried by the rotating part of the transmission. This is furtherevident because said figure shows that where a fluid passage passes from a stationary element to said rotating element a slip ring is provided as in the engine crank shaft bearing 2| or the oil emission passage as 11 from the rotatingv sleeve 281, to the collector ring 18.

Whereas I have illustrated and described only one form of hydraulic transmission and two forms of control mechanism therefor, it is to be understood that the invention is not to be' limited to the forms shown which are merely illustrative and tosome extent merely schematic;

What is claimed is:

1. In a hydraulic power transmission, a power supply shaft, a power delivery shaft, a 'hydraulic displacement device connected between said power supply and power delivery shafts and a second hydraulic displacement device connected between said power supply shaft and a stationary member, passages fory working fluid connecting said devices, and valve means for controlling the fiow of the working fluid, means responsive at certain times only to the speed of the power supply shaft and only-to the speed of the power delivery shaft at other times for controlling said valve.

2. In a hydraulic power transmission, a power supply shaft, a power deliveryshaft, a hydraulic means for controlling the flow of the working fluid to vary said speed ratio said means comprising a working fluid controlling valve, a piston for moving said valve, a cylinder in which said piston operates, a pump driven by one of said shafts for circulating a fluid, a metering valve in said fluid circuit; and a connection from a point in said fluid circuit vbetween saidpump and said metering valve and extending to said cylinder.

3. In a hydraulic power transmission, a power supply shaft, a power delivery shaft, a hydraulic displacement device connected between said power supply and power delivery shafts for causing said power supply shaft to operate said power delivery shaft at various speed ratios, passages for working fluid, and means for controlling the flow of the working fluid to vary said speed ratio, said means comprising a working fluid controlling valve, a piston for moving said valve, a cylinder in which said piston operates, a pump driven by one of said shafts for circulatinga fluid, a metering valve in said fluid circuit and a connection from a point in said fluid circuit between said pump and said metering valve and extending to said cylinder, and manual means for controlling said metering valve.

4. In a hydraulic power transmission, a power supply shaft, a power delivery shaft, a hydraulic displacement device connected between said power supply and power delivery shafts for causing said power supply shaft to operate said power delivery shaft at variousspeed ratios, passages for working fluid, and means for controlling the flow of the' working fluid to vary said speed ratio said means comprising a working fluid controlling valve, a piston for moving said valve, a cylinder in which said piston operates, a pump driven by one of said shafts for circulating a uid, a metering valve in said uid circuit and a connection from a point in said fluid circuit between said pump and said metering valve and extending to said cylinder, means'for controlling the amount of power supplied tosaid power supply shaft and connections from said power supply controlling means for varying the setting of said metering valve.

5. In a hydraulicpower transmission', a power supply shaft, a power delivery shaft, a hydraulic displacement device connected between said power supply and power delivery shafts for causing said-power supply shaft to operate said power delivery shaft at various speed ratios, passages for working fluid, and means for controlling the flow of the working fluid to vary said speed ratio said means comprising a working fluid controlling valve, a piston for moving said' valve, a cylinder in which said piston operates, a pump driven by one of said shafts for circulating a uid, a metering valve in said fluid circuit and a connection from a point in said fluid circuit between said pump and said metering valve and extending to said cylinder, spring means to oppose the movement of the piston by said fluid and manual means to control said spring means.

6. In a hydraulic power transmission, a power Supply shaft, a power delivery shaft, a hydraulic displacement device connected between sai'd power supply and power delivery shafts for causing said power supply shaft to operate said power delivery shaft at various speed ratios, passages for working fluid, and means for controlling the flow of the working fluid to vary said speed ratio said means computing a working-duid controlling valve, a piston for moving said valve, a cylinder in which said piston operates, a pump driven by one .of said shaftsfor circulating a fluid, a, metering valve in said fluid circuit and a connection from a point in said fluid circuit between said pump and said metering valve and extending to said cylinder, and means whereby the shifting of the fluid controlling valve from one position toward another causes the metering valve to he adjusted to favor said shifting.

'7. In a combined hydraulic power transmission and hydraulic brake, a power supply shaft, a power delivery shaft, a hydraulic displacement device connected between said power supply and power delivery shafts and a second hydraulic displacement device connected between said power supply shaft and a stationary abutment, passages for working fluid connecting said devices, and means for controlling the ow of the Working fluid so as at a certain time to block flow power delivery shafts and a second hydraulic displacement device connected between said power supply shaft and a stationary abutment, passages for working uid connecting said devices, and means for controlling the flow of the working fluid so as to cause said power supply shaft to drive said power delivery shaft at various speed ratios and means operating against said abutment to apply a reverse torque to said ypower supply shaft and means for applying an approximately equal forward torque to the power supply shaft.

9. In a hydraulic power transmission, a power supply shaft, a power delivery shaft, a hydraulic displacement device connected between said power supply and power delivery shafts for causing said power supply shaft to operate said power delivery shaft at various speed ratios, passages for Aworking fluid, and meansfor controlling the flow of the working fluid to vary said speed ratio said means comprising a working uid controlling valve, a piston for moving said valve, a cylinder in which said piston operates, a pump driven byone of said shafts for circulating a fluid, a metering valve in said fluid circuit and a connection from a point in said fluid circuit between said pump and said metering valve and extending to said cylinder, land a speed controlled bleeder valve'in said fluid circuit,

10. In a combined hydraulic power transmisdevice connected between saidl of the working fluid so as to apply a reverse tortorque.

HANS THOMA.

sion and hydraulic brake,a power supply shaft, 

